Template derivative for forming ultra-low dielectric layer and method of forming ultra-low dielectric layer using the same

ABSTRACT

A reactive cyclodextrin derivative or a reactive glucose derivative is used as a template derivative for forming an ultra-low dielectric layer. A layer is formed of the reactive cyclodextrin derivative or the reactive glucose derivative capped with Si—H and then cured in an atmosphere of hydrogen peroxide to form the ultra-low dielectric layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Korean patent applicationnumbers 10-2006-0135737 filed on Dec. 27, 2006 and 10-2007-0042106 filedon Apr. 30, 2007 and to U.S. Pat. No. 8,202,807 filed Dec. 27, 2007,which are incorporated herein by reference in their entirety. Thepresent application claims priority to U.S. Pat. No. 8,202,807 filedDec. 27, 2007.

BACKGROUND OF THE INVENTION

The present invention relates to a template derivative for forming anultra-low dielectric layer, and a method of forming the ultra-lowdielectric layer using the same, and more particularly, to a templatederivative for forming an ultra-low dielectric layer which is capable offorming an ultra-low dielectric layer with superior mechanical strength,and a method of forming the ultra-low dielectric layer using the same.

With the requirement for high integration and high speed forsemiconductor devices, the line width of metal wiring and the spacebetween the metal wirings have been rapidly reduced over time.Particularly, with the reduction in the distance between the metalwirings, this causes an increased parasitic capacitance between themetal wirings under the interposition of an insulation layer.

Therefore, various process technologies for lowering the resistance ofthe metal wiring and reducing the parasitic capacitance have beenstudied. As part of the technology, there have been attempts to use lowresistance materials, such as copper (Cu) instead of existing aluminum(Al), as the metal wiring material, and to use a low dielectric materialhaving a dielectric constant k of approximately 3.0, instead of SiO₂having the dielectric constant k of 4.0, or fluorinated silicon glasshaving the dielectric constant k of 3.5, as an insulation layer materialformed between the metal wirings.

Also recently, studies of ultra-low dielectric layers having adielectric constant k of 2.2 to 2.5 are actively in progress. Inrelation to this, there has been an attempt for a nanotemplating methodin which a thermally unstable pore generating resin, such as a porogen,is used as a nanotemplate and dispersed into an inorganic matrix, andthen pores are introduced into the inorganic matrix through a hightemperature heat treatment to form an ultra-low dielectric layer. Atthis time, it is important that the matrix containing pores should havesuperior mechanical and dielectric characteristics and, at the sametime, the pore should have a very small size and a low connectivity.

Meanwhile, the ultra-low dielectric layer may be deposited through achemical vapor deposition (CVD) process or a spin coating process.

In the use of the CVD process, a silicon based monomer containing anon-reactive porogen is deposited alone, or the non-reactive porogen anda matrix are co-deposited together to form the ultra-low dielectriclayer. However, because the use of the CVD process is not accompaniedwith a chemical bonding of the two materials, i.e. the non-reactiveporogen and the matrix, the use of the CVD process has the problem thatit is impossible to inhibit clumping of the non-reactive porogen.

The use of the spin coating process is better than the use of the CVDprocess to lower the dielectric constant. However, the use of the spincoating process is problematic in that it is difficult to control poremorphology, and particularly the pores are connected with one anotherwhen the pore content exceeds 20%, and also the mechanical strength israpidly reduced with an increase in the pore content.

Therefore, a method of forming the ultra-low dielectric layer using areactive porogen such as cyclodextrin derivative is desired.

FIG. 1 is a view illustrating a cyclodextrin derivative.

As shown, the cyclodextrin derivative is formed using cyclodextrin as aprecursor and through an allylation reaction using allylbromide and ahydrosilylation reaction using trialkoxysilane, and has a structurecapped with the trialkoxysilane.

In FIG. 1, a reaction group R represents H, and R′ represents(CH₂)_(n)—SiH3.

Since this reactive porogen can undergo a sol-gel reaction with anorganic silicate matrix precursor unlike the existing non-reactiveporogen, such as poly-carprolactone and poly-methylmethacrylate, theultra-low dielectric layer formed using this reactive porogen hasadvantages that it is superior not only in the aspect of the poremorphology but also in the aspect of the mechanical strength.

However, since the reactive porogen, such as cyclodextrin, has very lowreactivity with the matrix, compared to the reactivity of the matrixitself, a clumping of the reactive porogen is generated when the porogencontent is more than a specific amount, and thus the pore morphologyproblem cannot be solved. Particularly, when the porogen content ishigh, the pore size and the pore connectivity are increased and thus itis impossible to obtain the desired ultra-low dielectric layer.

Also, even in the ultra-low dielectric layer formed using the reactiveporogen, such as cyclodextrin, the pore size rapidly increases resultingin the rapid decrease in the mechanical strength when the dielectricconstant is uniformly and continuously lowered. Particularly, a curingprocess using ultraviolet rays should be followed to solve this problem,which makes the process more complicated.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a templatederivative for forming an ultra-low dielectric layer capable of solvingthe pore morphology problem, and a method of forming the ultra-lowdielectric layer using the same.

Also, embodiments of the present invention are directed to a templatederivative for forming an ultra-low dielectric layer capable of formingan ultra-low dielectric layer with superior mechanical strength, and amethod of forming an ultra-low dielectric layer using the same.

In one embodiment, a template derivative for forming an ultra-lowdielectric layer is composed of a cyclodextrin derivative represented bythe following formula 1:

wherein, in the formula 1, n is an integer of 6 to 8 and m represents aninteger of 1 to 3.

The cyclodextrin derivative is formed through an allylation of areactive cyclodextrin using allylbromide and a following hydrosilylationof the allylated reactive cyclodextrin with SiH₄ gas.

The cyclodextrin derivative is capped with Si—H.

The cyclodextrin derivative is selected fromhexakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-α-cyclodextrin},heptakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-β-cyclodextrin} andoctakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-γ-cyclodextrin}.

In one embodiment, a method of forming an ultra-low dielectric layercomprises forming a layer using the cyclodextrin derivative representedby the above formula 1; and curing the formed layer using thecyclodextrin derivative in an atmosphere of hydrogen peroxide.

The step of forming the layer using the cyclodextrin derivative isperformed using the cyclodextrin derivative together with a silicate lowdielectric matrix.

The silicate low dielectric matrix includes one silicate precursorselected from polymethylsilsesquioxane and polymethylsilsesquioxanecopolymer.

The step of forming the layer using the cyclodextrin derivative isperformed in a spin-on method.

The step of curing the layer formed using the cyclodextrin derivative inan atmosphere of hydrogen peroxide is performed at a temperature of 100to 250° C. for 30 to 120 minutes.

The method may further comprise, after the step of curing the layerformed using the cyclodextrin derivative in an atmosphere of hydrogenperoxide, the step of heat treating the cured layer.

The step of heat treating the cured layer is performed at a temperatureof 350 to 400° C. for 30 to 120 minutes.

In another embodiment, a template derivative for forming an ultra-lowdielectric layer is composed of a glucose derivative represented by thefollowing formula 2:

wherein, in formula 2, R represents (CH₂)_(n)—SiH₃ and n represents aninteger of 1 to 3.

The glucose derivative is formed through an allylation of a reactiveglucose precursor using allylbromide and a following hydrosilylation ofthe allylated reactive glucose precursor with SiH₄ gas.

The glucose derivative is capped with Si—H.

In another embodiment, a method of forming an ultra-low dielectric layercomprises forming a layer using the glucose derivative represented bythe above formula 2; and curing the layer in an atmosphere of hydrogenperoxide.

The step of forming the layer using the glucose derivative is performedusing the glucose derivative alone or together with a silicate lowdielectric matrix.

The silicate low dielectric matrix includes one silicate precursorselected from polymethylsilsesquioxane and polymethylsilsesquioxanecopolymer.

The step of forming the layer using the glucose derivative is performedin a spin-on method.

The curing step is performed at a temperature of 100 to 250° C. for 30to 120 minutes.

The method may further comprise, after the step of curing the layerformed using the glucose derivative in an atmosphere of hydrogenperoxide, the step of heat treating the cured layer.

The heat treatment is performed at a temperature of 350 to 400° C. for30 to 120 minutes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a cyclodextrin derivative.

FIG. 2 shows a chemical formula for a reactive cyclodextrin derivativein accordance with an embodiment of the present invention.

FIG. 3 shows a chemical formula for a glucose derivative in accordancewith another embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

In a preferred embodiment of the present invention, a layer is formedusing a cyclodextrin derivative capped with Si—H as a templatederivative for forming an ultra-low dielectric layer, and then cured inan atmosphere of hydrogen peroxide to form the ultra-low dielectriclayer. At this time, the layer formed using the cyclodextrin derivativeis formed using the cyclodextrin derivative alone or together with asilicate low dielectric matrix.

In this case, a sol-gel reaction is generated in which Si—H bonding in asol state of the cyclodextrin derivative is changed into Si—OH bondingin a sol state, and then the Si—OH bonding in a sol state is changedinto Si—OH bonding in a gel state through a curing treatment in anatmosphere of hydrogen peroxide. At this time, the reactivity of theSi—OH with the silicate low dielectric matrix is much superior to thereactivity of the Si—OR (R: methyl or ethyl) of a conventional reactiveporogen with the silicate low dielectric matrix.

Therefore, in the present invention, since the porogen, having a size ofseveral nanometers, can be dispersed independently into the silicate lowdielectric matrix even when the porogen content is high, it is possibleto form the ultra-low dielectric layer having superior mechanical anddielectric characteristics and, at the same time, having pores with avery small size and a low connectivity.

Also, in another preferred embodiment of the present invention, a layeris formed using, as a template derivative for forming an ultra-lowdielectric layer, a glucose derivative capped with Si—H alone ortogether with the conventional silicate low dielectric matrix and thencured in an atmosphere of hydrogen peroxide to form the ultra-lowdielectric layer.

In this case, like the aforementioned case, a sol-gel reaction isgenerated in which Si—H bonding in a sol state of the glucose derivativeis changed into Si—OH bonding in a gel state through the curingtreatment in the atmosphere of hydrogen peroxide. At this time, thereactivity of the Si—OH with the silicate low dielectric matrix is muchsuperior to the reactivity of the Si—OR (R: methyl or ethyl) of theconventional reactive porogen with a silicate low dielectric matrix.

Therefore, in the present invention, since the porogen, having a size ofseveral nanometers, can be dispersed independently into the silicate lowdielectric matrix, even when the porogen content is high and the porehas a small size of less than 1 nm and low connectivity due to the smallsize of the glucose particle, it is possible to form the ultra-lowdielectric layer having superior mechanical strength, and no follow-upUV treatment is needed.

Hereafter, preferred embodiments of the present invention are describedin detail with reference to the accompanying drawings.

FIG. 2 shows the chemical formula of a reactive cyclodextrin derivativein accordance with an embodiment of the present invention.

As shown, a template derivative for forming an ultra-low dielectriclayer in accordance with an embodiment of the present invention is acyclodextrin derivative capped with Si—H. The cyclodextrin derivative isformed using a reactive cyclodextrin as a precursor and through anallylation of the reactive cyclodextrin using allylbromide and afollowing hydrosilylation in which the allylated reactive cyclodextrinis reacted with SiH₄ gas. Examples of the cyclodextrin derivative mayinclude hexakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-α-cyclodextrin},heptakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-β-cyclodextrin} andoctakis{2,3,6-tri-O-(3-trihydrosilylpropyl)-γ-cyclodextrin}.

In FIG. 2, n is an integer of 6 to 8 and m is an integer of 1 to 3.

A method of forming an ultra-low dielectric layer in accordance with anembodiment of the present invention using the reactive cyclodextrinderivative is as follows.

Firstly, a thin layer is formed over a semiconductor substrate using thereactive cyclodextrin derivative according to a spin-on method. At thistime, the thin layer is formed using the cyclodextrin derivative aloneor together with a silicate low dielectric matrix. The silicate lowdielectric matrix includes one silicate precursor ofpolymethylsilsesquioxane and polymethylsilsesquioxane copolymer.

Next, the thin layer formed of the reactive cyclodextrin derivative issubjected to a curing treatment in an atmosphere of hydrogen peroxide.The curing treatment is performed at a temperature of 100 to 250° C. for30 to 120 minutes. During the curing treatment, a sol-gel reaction isgenerated in which Si—H bonding in a sol state, which has capped thecyclodextrin derivative, is changed into Si—OH bonding in a sol state,and then the Si—OH bonding in a sol state is changed into Si—OH bondingin a gel state. At this time, the reactivity of the Si—OH with thesilicate low dielectric matrix is much superior to the reactivity of theSi—OR of the conventional reactive porogen with the silicate lowdielectric matrix.

Therefore, if the ultra-low dielectric layer is formed using thereactive cyclodextrin derivative in accordance with an embodiment of thepresent invention, since the porogen having a size of several nanometerscan be dispersed independently into the silicate low dielectric matrixeven when the porogen content is high, it is possible to form theultra-low dielectric layer having superior mechanical and dielectriccharacteristics and, at the same time, having a pore with a very smallsize and a low connectivity.

Subsequently, the cured thin layer is heat treated at a temperature of350 to 400° C. for 30 to 120 minutes to form the ultra-low dielectriclayer in accordance with an embodiment of the present invention.

As described above, in an embodiment of the present invention, since alayer is formed using the reactive cyclodextrin derivative capped withSi—H bonding and then subjected to a curing treatment in an atmosphereof hydrogen peroxide to form the ultra-low dielectric layer, it ispossible to enhance the mechanical and dielectric characteristics of theultra-low dielectric layer and reduce size and connectivity of the porein the ultra-low dielectric layer.

FIG. 3 shows a chemical formula of a glucose derivative in accordancewith another embodiment of the present invention.

As shown, a template derivative for forming an ultra-low dielectriclayer in accordance with another embodiment of the present invention isa reactive glucose derivative capped with Si—H. The reactive glucosederivative capped with Si—H is formed through an allylation reaction ofa glucose precursor using allylbromide and a following hydrosilylationreaction of the allylated glucose precursor using SiH₄ gas.

In FIG. 3, a reaction group R represents (CH₂)_(n)—SiH3 and n is aninteger of 1 to 3.

A method of forming an ultra-low dielectric layer in accordance withanother embodiment of the present invention using the reactive glucosederivative is as follows.

A thin layer is formed over a semiconductor substrate using the reactiveglucose derivative according to a spin-on method. At this time, the thinlayer is formed using the glucose derivative alone or together with aconventional silicate low dielectric matrix. The silicate low dielectricmatrix includes one silicate precursor of polymethylsilsesquioxane andpolymethylsilsesquioxane copolymer.

Next, the thin layer formed of the glucose derivative is subjected to acuring treatment at a temperature of 100 to 250° C. for 30 to 120minutes in an atmosphere of hydrogen peroxide. During the curingtreatment, a sol-gel reaction is generated in which Si—H bonding in asol state which has capped the glucose derivative is changed into Si—OHbonding in a sol state, and then the Si—OH bonding in a sol state ischanged into Si—OH bonding in a gel state, and the Si—OH bonding hassuperior reactivity with the silicate low dielectric matrix compared tothe conventional case.

Therefore, if the ultra-low dielectric layer is formed using thereactive glucose derivative, since the porogen having a size of severalnanometers can be dispersed independently into the silicate lowdielectric matrix even when a porogen content is high, it is possible toform the ultra-low dielectric layer having a low pore connectivity, asuperior mechanical strength and a low dielectric constant.

Subsequently, the cured thin layer is heat treated at a temperature of350 to 400° C. for 30 to 120 minutes to form the ultra-low dielectriclayer using the reactive glucose derivative in accordance with anotherembodiment of the present invention.

As described above, in another embodiment of the present invention,since a layer is formed using the reactive glucose derivative cappedwith Si—H bonding and then subjected to a curing treatment in anatmosphere of hydrogen peroxide to form the ultra-low dielectric layer,it is possible to enhance the mechanical and dielectric characteristicsof the ultra-low dielectric layer and reduce size and connectivity ofthe pore in the ultra-low dielectric layer.

Although specific embodiments of the present invention have beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and the spirit of theinvention is as disclosed in the accompanying claims.

1. A method of forming an ultra-low dielectric layer using a templatederivative for forming ultra-low dielectric layer, comprising the stepsof: forming a layer using a cyclodextrin derivative represented by thefollowing formula:

wherein, in the formula, n is an integer of 6 to 8 and m represents aninteger of 1 to 3, and the cyclodextrin derivative is capped with Si—H;and curing the layer formed using the cyclodextrin derivative in anatmosphere of hydrogen peroxide.
 2. The method according to claim 1,wherein the step of forming the layer using the cyclodextrin derivativeis performed using the cyclodextrin derivative together with a silicatelow dielectric matrix.
 3. The method according to claim 2, wherein thesilicate low dielectric matrix includes one silicate precursor selectedfrom polymethylsilsesquioxane and polymethylsilsesquioxane copolymer. 4.The method according to claim 1, wherein the step of forming the layerusing the cyclodextrin derivative is performed in a spin-on method. 5.The method according to claim 1, wherein the step of curing the layerformed using the cyclodextrin derivative in an atmosphere of hydrogenperoxide is performed at a temperature of 100 to 250° C. for 30 to 120minutes.
 6. The method according to claim 1, further comprising, afterthe step of curing the layer formed using the cyclodextrin derivative inan atmosphere of hydrogen peroxide, the step of heat treating the curedlayer.
 7. The method according to claim 6, wherein the step of heattreating the cured layer is performed at a temperature of 350 to 400° C.for 30 to 120 minutes.